System of control



Patented Dec. 11, 1923.

UNITED STATES PATENT OFFICE- HENRY D. MURDOCK, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- 'VANIA.

SYSTEM OF CONTROL.

Application filed March 30, 1921.

[0 all "whom it may concern:

Be it known that I, HENRY D. Munnoon, a citizen of the United States, and a resident of d' ilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Systems of Control, of which the following is a specification.

My invention relates to motor-control systems and it has particular relation to systems for the protection of a plurality of electrically-connected dynamo-electric machines from excessive overloads such, for example, as may occur upon a plurality of motors for driving an electric car or locomotive.

An object of my invention is to protect a motor-control system from an excessive rush of current in any part thereof. More specifically stated the object of my invention is to provide means for protecting a motor-control system from an electrical overload upon any one of a plurality of dynamo-electric machines in the system by opening a circuit-breaker which connects the dynamo-electric machines to a source of electrical energy and preventing the operation of means for reversing the connections of the dynamo-electric machines during energization thereof above a predetermined value during dynamic braking.

Heretofore, there have been means for protecting a motor-control system from an overload 'upon the system, but such protective means have been slow to respond to overload conditions, when the dynamo-electric machines were connected in a certain arrangement. V

Briefly speaking, my invention consists in providing a relay having two actuating coils, which are respectively connected in series relation with a plurality of motors for governing the movement of a circuitlHOHl-IBI' and. a main reverser.

These actuating coils are so arranged that, when the energization of the motors is substantially equal, the magnetizations of the a .:tuat-ing coils s0 oppose one another that the relay will not operate. Upon an electrical overload occurring in one of the motors, the balanced condition of the opposing magnetic fields of the actuating coils of the relay will no longer be established, and the more strongly energized actuating Serial No. 456,859.

coil will cause the relay to assume its closed position, thereby opening the circuit-breaker. The main reverser is rendered inoperative during dynamic braking by the relay being actuated to its closed position, as the actuating coils thereof assist one another under such conditions.

For a better understanding of my invention, reference may be made to the accompanying drawings,

Figure 1 of which is a schematic view of a motor-control system embodying my invention;

Fig. 2 is a sequence chart of well-known form, showing the order of closure of the contactors of the control system shown in F ig. 1, and

Fig. 3 is a diagrammatic view of a plurality of auxiliary circuits for governing a plurality of switches shown in F ig. 1.

Referring to Fig. 1, a plurality of motors 1, 2, 3 and 4 are energized from a suitable source of electrical energy, such, for example, as a trolley 5, through a trolley-pole 6, a line switch or circuit-breaker 7, one or more accelerating contactors S, 9, l1 and 12 and a starting resistor 13.

The motors l and 2 are permanently con nected in parallel relation and have series field-magnet windings 15 and 16, respectively, and armatures l7 and 18, respectively. The motors 3 and 4 are permanently connected in parallel relation and have series fieldmagnet windings 19 and 21, respectively, and armatures 22 and 23, respectively.

The group of motors 1 and 2 may be connected in series relation with the motors 3 and 4 by means of a series contactor 24; and may be connected in parallel relation with the motors 3 and -l by means of a parallel contactor 25 and a ground contactor 26.

Referring to Fig. 3, a master controller 2-8. having an off position and plurality of operative positions a to 2', inclusive, governs the acceleration of the motors 1, 2, 3 and 4. The motors may be connected for forward operation by means comprising a master reverser 29 having an off position, a forward position and a reverse position. The master reverser 29 governs the movement of a main reverser 31 having a forward and a reverse position.

The main reverser 31 comprises a movable drum 32, which may be actuated to either its forward or its reverse position by of suitable actuating coils 3 and 34:, respectively.

For the sake of simplicity, only the connections for reversing: the connections of the series field-magnet winding 15 to the armature 17 of the motor 1 is shown. The series field-magnet windings 16, 19 and 21 of the motors 2, 3 and l: have their connections to the corresponding armatures 18, 22 and 2S reversed in the same manner, that is, by disengaging a plurality of forward contact segments 30 forming' part of the main reverser .31 from contact teii'ininals 30 and by actuating the reverse contact segments 30 into engagement with the contact terminals 30. All of the accelerating contactors 8, 9, 11 and 12, series contactor 2d, parallel contactor 25 and ground contactor .26 have their actuating coils energized through a control resistor 35, in accordance with well-known practice.

The energization of the actuating; coils 33 and 34 of the main reverser 31 and the actuating coil of the circuit-brealqer 7 are groverned by the relay 36, which normally closed. The energization of the actuating; coil of relay 86 is governed by relays 37 and 88, both or" which are normall in their open positions.

The relay 3'? is provided with two uctuating coils 39 and 4C1, which are connected in series relation with the armature l7 ot the motor 1 and the armature 18 oi? the motor 2, respectively The relay 38 pro with a plurality of actuating c ils 44, which are connected in series relation with the armature 22 oi": the motor and the armature 23 of the motor i. respectively.

The actuating coils 39 and 41 ot the relay 3? are so designed and positional upon the relay 3,7, that, when their energization is substantially equal, they neutralize one another and the relay 37 remains in its open position. It, for any reason, the magnetization of either the actuating coil 39 or the coil 41 should become greater than the other, the relay 37 will close.

The actuating coils 48 and. l l of the contactor 88 are so arranged and designed, that, when their magnetic iields oppose each other and ar substantially equal, movable contact member of the relay remains in its open position. it the energization of either of the actuating coils or e4. becomes greater by a predetermined value than that of the other, the movable contact member or" the relay 88 will be actuated to its closed position.

The operation of the system embodyi my invention is begun by aituating the master reverser 29 to its rorward position and then actuating the ma l to position a. circuit lislie from the trollev throupgl contact tern ls 4(3 and cont: scenic-at "ti" oi the master controller L8 and control resistor to ground.

ll hen the control resistor 35 is energized and master reverser29 in its for ard position, and the main reverser Fill in its reverse position, the actuating coil 33 or? the main reverser 81 is energized by a circuit extendin 1 cm control resistor 35 tl'irough the contact members of relay 56, actuating coil of main rcyerser Ell, contact terminal 48, contact segment 4:9, contact terminal 51 of the main reverser 31, contact terminal of the master reyer'e 29. contact L ment and contact terminal 5% to grouse.

The energization of the actuating coil 33 causes the main reverser to be actuated to its forward position. thereby breaking the circuit comprising the actuating coil and establishing a circuit from the control resistor through the contact members of re lay 36, actuating coil of circuit breaker 7, contact terminal ot main reverser i-l, con.- tact segment 4-9, contact terminal 51 of main reverser contact terminal 52 oi master reverser 29, contact segment 53 and contact terminal 54; to ground.

The actuating coils of the accele. contactor 8 and of series contactor 1 energized simultaneously with the V of the line switch 7 by a plurality of circuits that it is considered unnecessary to trace. ll hen the lineswitch T, accelerating contactor 8 and series eontactor 2%: :rr closed, a circuit is established from the trol. ley 5 through line switch 7, accelerating contactor 8, starting resistor 13, parallel-connected actuating" coils 89 and a l of the re lay 3T. armatures 1i and 18 and series field n'iagnet windings and 16 of the parallelconnected motors .i and respectiyely, contact members of series contactor parallel- (:ODHGCtGf actuating coils a3 and art oi? the relay 3S, tit-matures and 2?) ani series field-magnet windings 19 and 21 ot the parallel-connected motors 3 and a, respectively, to ground.

The motors 1, 2, S and at are accelerated by shunting portions of the starting resistor '13 by the closure of the accelerating contacl'ors S. 9. ll and 12 in accordance with the sequence chart shown in Fig. 2. upon the master controiler l7 being actuated through, positions (2;; l, c and (7 to a, which the tull-series ruiminn position.

The motors i 3 t d are further urcelerated byactuating the master controller l? through the transition position to position fithereby opening the series contactor 2e and accelerating contactor 8 and closing the parallel contact-or and the ground contact-or 26, in accordance with the sequence chart shown in hi 2. l

The motors arcsgain accelerated upon LII lllll full parallel running position, by shunting various portions of the resistor 13 in accordance with the sequence chart shown in Fig. 2.

This method of acceleration is well known in the art and the control circuits for the contactors have been omitted except in so far as they are necessary to describe my invention. If, for any reason, a short circuit occurs, caused by a ground upon any of the motors 1, 2, 3 and 4, the operation of my protective system is as follows:

If, for example, the short-circuitoccurs upon the motor 2, causing an excessive rush of cur ent through the actuating coil 41 of the relay 37, the energization of the actuating coil. 41 will become sufiiciently greater than that of the actuating coil 39 of the relay 37 to cause the contactor of the relay 37 to assume its closed position, thereby establishing a circuit through the control resistor 35, actuating coil of relay 36, and contact members of relay 37 to ground.

The energization of the actuating coil 36 causes the movable contact member of the relay 36 to assume its open position, thereby opening a circuit comprising the actuating coil of the circuit-breaker 7, causing the circuit-breaker to assume its open position, and thus de-energize the motors 1, 2, 3 and 4.

Circuits comprising the actuating coils 33 and 34 are also broken upon the relay 36 assuming its open position, thereby making it impossible to move the main reverser 31 from its forward position to its reverse position.

The relay 36 will not return to its closed position until the master controller 47 has been actuated to its off position, since a holding circuit for the relay 36 is provided by a circuit from the control resistor 35 through the actuating coil of relay 36 and an auxiliary contact member 57 of the relay 36 to ground.

If a sufliciently heavy overload occurs on either the motor 3 or the motor 4, then the corresponding actuating coil 43 or 44 will be so excessively energized that it will cause the movable contact member of the relay 38 to assume its closed position, thereby establishing a circuit from control resistor 35 through the actuating coil of the relay 36 and the contact members of the relay 38 to ground.

It, for any reason, one of the motors 1, 2, 3 or 4 becomes de-energized, then the corresponding one of the actuating coils 39, 41, 43 or 44 is likewise de-energized and the actuating coil of the corresponding relay, 37 or 38, that remains energized will cause the movable contact member to assume its closed position,

It is apparent that, by means of my invention, I have provided means for rapidly opening the circuit-breaker of a control system upon the occurrence of an overload or no load in any one of a plurality of motors operating in a control system. It is also apparent that systems embodying my invention may be employed with generators or other electrical devices in substantially the same manner as is shown for the motors of an electric car or locomotive.

If electrical braking of the motors is required, the master controller 47 is actuated to its off position and the master reverser 29 is actuated to its reverse position, in accordance with the usual practice, after which the master controller 28 is again actit ated to its first position.

A circuit is then established from the trolley 5 through contact terminals 46 and contact segment 47 of the master controller 28 and control resistor 35 to ground. A circuit comprising the reverse actuating coil 34 of the main reverser 31 is established from the control resistor 35 through the contact members of the relay 36, actuating coil 34 of the main reverser 31, contact terminal 58 of the main reverser 31, contact segment 59, contact terminal 61, contact terminal 62 1 of the master reverser 29, contact segment 63 and contact terminal 54 to ground.

The energization of the reverse actuating coil 34 causes the main reverser 31 to be actuated to its reverse position, thereby establishing a circuit from the control resistor 35 through the contact members of the relay 36, the actuating coil of circuitbreaker 7, contact terminal 64 of main reverser 31, contact segment 59, contact terminal 61, contact terminal 62 ot the master reverser 29, and contact segment 63 and contact terminal 54 of the master reverser 29 to ground.

The terminals of the series field-magnet windings 15, 16, 19 and 21 of the motors 1, 2, 3 and 4, respectively, are now reversed with relation to the armature terminal and ground by the contact terminals 30 of the main reverser 31 being engaged by the re verse contact segments 30". The motors are energized from the trolley 5 through line switch 7, accelerating contactor 8 and starting resistor 13. The operation of the motors during these conditions is known as plugging.

It dynamic braking is desired, the master controller 47 is again actuated to its oft position, thereby de-energizing the control resistor 35 and, consequently, the actuating coils of line switch 7, accelerating con actor 8 and series contactor 24.

Two dynamic braking circuits or closed loops will be established, one of which comprises armature 17 and series field-magnet winding 15 of the motor 1, series field-magnet winding 16 and armature 18 of motor 2 and actuating .coiils 1-1 and 39 of the ore)- load relay 37. The second dynamic braking circuit is established through the parallelconnccted motors 3 and and comprises armature 22 and series field-magnet Winding 19 of the motor 3, series field-magnet \vi-nr ing 21 and armature 23 of the motor land the actuating coils id: and 43 of the relay It will be noted tltiat the .uiagnetizations of the actu: "ting: coils and l]. of the relay 3? no longer oppose each ot er, as the current jl'tl\TGiSl]" both actu no coi. the same direction; consequently. the tact FPE1YllDGi"37 assuin closed posit... Likewise, the actuating coils 1 and 44-. are energized in the same manner, to thereby close the relay 38. So long; as either the relay 37 or :he relay 38 is in its closed position, it will be impossible to actuate the main reverscr 3;, for as soon as the control resistor 3:5 is energizer: the actuating: coil ed and a cirot the relay 36 \vill be one-r actuating coil cuit comprisin either the 33 or the actuating coil 34: of .the ma n reverser 31 will be broken.

it is advantageous to prevent movement of the main reverser 31 from either its forivard position to its reverse position, or vice versa, as the heavy current resulting from dynamic braking Would cause severe arcingbetween the contact terminals and the drum segments of the main revcrser 31 should the circuit be opened, While this heavy current continues.

It is apparent that a push-button may he placed in circuit with the actuating coil of the relay 36, if desired. so to permit the main reverser 31 to be thrown, if any emergency existed which would make it imperatire.

In a twoanotor control system, any occurrence oi? mot-or flashing or groundino' may be safeguarded against by eniploy',.ig a relay, for the same purpose as previoi, 'ly described, having two actuating coils. one of the coils being placed in circuit with tho moto s and adjacent to the trolley, the other of said coilsbeing; in circuit with the-motors and adjacent to ground.

While I have (.cscribed my invention. in its preferred form it is apparent that minor modifications may be made in thc arrangenientoii the circuits and apparatus employed Without departing from the spirit of my invention. l desire, therefore, to be limited only by the scope of the appended claims.

I claim as my invention:

1. The combination with a plurality of.

motors and means comprising a controller having a plurality oi? positions for energizing said motors. of means for de-energizing said motors, aid means compri ing a plu rality of actuating coils respec ively con.- nected in series relation with said in tor-s, and inieans for :preventing said do energiz- Lern r? ing means from becominginoperative until after said controller has been actuated to predetermined pos tion. 2. The combination with a plurality oi? motors and a source of electrical energy of a circuit-breaker for connecting; said motors to said source, a controller having a plurality of positions for govcrnino said circuit breaker, and means comprising a plurality of actuating coils for governing said circuitbreaker, each. of said coils being in circuit with a di'li'erent one of said motors, and means for preventing said circuit breaker from closing after said first means has operated unless said controller actuated to its off position. 7

3. The combination with a plurality of dynamo-electric machines and means forencr-gizing said machines. of means comprisin a plurality ct relays for I: sald machines, one of said 1' a plurality of coils. each erg no means inoperative. and the other of said relays being; provided with means for -rendeizingit inc; erative after said first relay has operated.

l. The combination with plurality of dynamo-electric machines, 0. a source of electric energy, a circuit-b ll er having! an actuating coil for c, .1QCt-l.ilf said machines to said source, a relay provided with a holding circuit for deenergizing said coil, and means comprising a second relay having a plurality of actuating coils for governing the operation oi said first relay. the magnetization of the actuating; coils of said second relay neutraliZingeach other during normal operation oi? said machines.

5. The combination With a plurality of dyna1no-eleotric machines, of source of electrical energy, a circuit-breaker having an actuating coil for connectin said machines to said source, a relay for de-energizing the actuating coil of saidcircuitsbrealrer, and a said first relay, said second relay having its actuating coils in circuit with the respective machines.

6. The combination with a dynamo-electric machines, of means comprising a controller having a plurality of positions for energizing said machines, and

plurality of 'lIlBfLDS for deenergizing said machines upon theoccurrence oi"? a predetermined overload in one of said machines provided said overload is greater upon said one machine than upon another of said machines, and means comprising said de-energizing means for pr venting energizing ii -sail from or I til) lit)

crating until said controller has been actuated to a predetermined position.

7. The combination with a plurality of dynamo-electric machines, a controller for governing the speed of said machines and means for reversing the connections of said machines, of means comprising a plurality of relays for rendering said reversing means inoperative upon the energization of said machines above a predetermined value, one of said relays comprising a plurality of actuating coils, said coils being respectively connected in circuit with said machines, and another of said relays preventing said machines from being re-energized until after said controller has been actuated to its oil position.

8. The combination with a plurality of motors and a controller for governing the speed of said motors, of means for reversing the operation of said motors, said means being adapted for effecting dynamic braking during predetermined conditions, and means comprising a relay for preventing cessation of said dynamic braking until after the current traversing said motors has decreased below a predetermined value, and said controller has been actuated to its oil position.

9. The combination with a plurality of motors and a controller having a plurality of positions for governing said motors, of means for reversing the operation of said motors, said means being adapted for efiecting dynamic braking during predetermined conditions, and means for preventing cessation of said dynamic braking until after the current traversing said motors has decreased below a predetermined value, said preventing means comprising a relay having a plurality of actuating coils, said coils being respectively connected in series relaton with said motors, and means for preventing said motors from being re-energized prior to said controller being actuated to a predetermined position.

10. The combination with a plurality of motors, each having an armature and a field-magnet winding and a controller having a plurality of positions for governing the speed of said motors, of a main reverser having a forward and a reverse position for reversing the relation of each of said windings to the corresponding armature, means for actuating said main reverser to its forward and to its reverse position, and means comprising a relay having a plurality of actuating coils for preventing said actuating means from operating said main reverser during dynamic braking, each of said actuating coils being in circuit with a diflerent motor from any of the other actuating coils, and a second relay for preventing said main reverser from being actuated until said controller has been returned to a predetermined position.

11. The combination with a plurality of motors and means for reversing said motors, of a controller for governing the speed of said motors, a source of electrical energy, a circuit-breaker having an actuating coil for connecting said machine to said source, and means comprising a relay for governing the energization of the actuating coil of said circuit-breaker, and means comprising a second relay having a plurality of actuating coils for governing said first relay, the magnetization of said actuating coils of said second relay neutralizing each other during normal operation of said machines but cooperating to prevent said first relay from being actuated during dynamic braking of said motors, said first relay preventing said circuit breaker from operating until after said controller has been actuated to its ofl? position.

12. The combination with a plurality of motors, of means comprising a controller having a plurality of positions for energizing said motors, means for reversing said motors, said reversing means co-operating with said motors for effecting dynamic braking during predetermined conditions, and means comprising a plurality of relays, one of said relays having a plurality of actuating coils for governing said energizing means and said reversing means, the mag netization of said coils opposing and balancing each other during normal operation of said motors to render said relay inoperative but assisting each other during dynamic braking to prevent the operation of said reversing means, another of said relays rendering the system inoperative until after said controller has been actuated to a predetermined position.

In testimony whereof, I have hereunto subscribed my name this 18th day of March, 1921.

HENRY D. MURDOCK. 

